If you spend time understanding the science behind Roundup and glyphosate, its active ingredient, you soon realize that this is a safe chemical compared to many other chemicals, even ones liberally used in the home. Why is it then that so many people fear Roundup?
Probably the biggest reason is great promotion by the anti-Roundup and anti-Monsanto crowd. That is one powerful force that brings one misleading article after another to the attention of a lot of people.
I think that another reason for this fear is our inability to understand very small and very large numbers. A recent research study found glyphosate in natural water systems, and I have seen it posted by several people as proof of a real problem that needs to be feared. If these people simply understood small numbers, they would not fear the report or Roundup.
Glyphosate in Our Water
A recent study found that 41% of the 140 groundwater samples tested in Spain contained glyphosate.
The abstract title is “Determination of glyphosate in groundwater samples using an ultrasensitive immunoassay and confirmation by on-line solid-phase extraction followed by liquid chromatography coupled to tandem mass spectrometry.”
The author of a news article about the study took the data from the study and came up with this title: “Glyphosate, despite its low mobility in soils, is capable of reaching groundwater. 41% of 140 groundwater samples from Catalonia, Spain, contained high levels, technically beyond the limit of quantification.” Note the “contained high levels, technically beyond the limit of quantification”
The levels are in the ng/L range – that is not high levels.
What does “technically beyond the limit of quantification” mean? It certainly does not mean the levels were too high to measure – you simply dilute the sample. And if the levels were so low that they could not be detected, then they are certainly not high levels.
More gobbledygook to help convince people of the terrors of glyphosate.
They did find glyphosate in 41% of the samples. That means 59% had no glyphosate – a much more positive way to report things.
For this discussion, I’ll assume the work was well done and the data is accurate.
Understanding Small Numbers
The average amount of glyphosate in 41% of positive samples was 200 ng/L. A number like 200 sounds like a lot, and we humans really can’t visualize a ng (nano-gram), so this seems like a lot. But how much is it?
200 ng/L = 0.000,000,2 g/L
You might know that a gram is about the weight of a paperclip, but that does not really help to understand this number because it is so small.
“The EPA Allowable Daily Intake (ADI) for glyphosate is set at 1,750 µg (1.75 mg) per kg of body weight. The EU ADI is just 0.3 mg per kg body weight.” (ref 2). I’ll go with an average of 1mg/Kg.
The daily safe intake for someone weighing 70 Kg (150 pounds) is 70 mg. If you were drinking the average contaminated water in Spain, you would need to drink 350,000 L before you would reach this safe level. Or putting it in terms everyone understands – 1,000,000 beer-sized bottles. And that is the daily allowance.
How Toxic is Water?
The above calculation is informative, but I left out one very important detail. Water is also toxic, with an LD50 of 90 mL/Kg body weight. The 70 Kg person discussed above would have a 50% chance of dying after drinking just 6.3 L of water. They would almost certainly be dead long before they could drink the 350,000 L of glyphosate-laced water from Spain.
Interesting, probably only to a biochemist, is the fact that water would never kill you. By drinking water, your body would get its sodium/potassium levels out of whack, and that kills you. The water itself is not toxic.
Glyphosate in Cheerios
The same kind of arguments have been made for food products, especially Cheerios. With claims that they are laced with Roundup.
The truth is that all food products contain some glyphosate. Even organic caged chicken eggs contained it. But the levels in food are extremely low. “Fourteen of the twenty-four food items tested contained less than 75 ppb of glyphosate, which is equivalent to 75 µg of glyphosate per liter of testing solution. This is well below the ADI of 1,750 µg per kg of bodyweight per day”.
Roundup and Glyphosate
Bayer, owner of Monsanto, has been releasing numerous products using the Roundup brand name. These do not all contain glyphosate, while others contain glyphosate and much more toxic herbicides. One type of Roundup now contains vinegar and no glyphosate. Gardeners need to clarify which product they are talking about when they use the word Roundup. This post is about the traditional product containing glyphosate.
The issue of bioaccumulaton in the human body over time is raised in the breakfast foods article. This would seem to be a more serious concern than tiny doses from various foods. Have you tried to evaluate this potential problem? What are your thoughts?
I have not looked at it in detail. Most things are not bioaccumulated in the body. Our bodies re designed to deal with chemicals it does not want. Heavy metals are an exception and we need to be concerned about them.
How about calling Round-up a herbicide instead of a pesticide. Herbicide sounds a lot less threatning
All herbicides are pesticides.
If using the term herbicide gives people the feeling that the chemical is less threatening – which it might – then it would do no service to use the term. Herbicides can be just as harmful as any other type of pesticide, or less harmful. Each chemical needs to be evaluated as a stand-a-lone item.
The overuse of glyphosate is entirely due to GMO. Since the implementation of round-up ready crops (soybean, corn, cotton, etc) all GMO, the use of glyphosate has increased world wide.
https://enveurope.springeropen.com/articles/10.1186/s12302-016-0070-0
No it is not. Roundup was one of the most commonly used pesticides before GMO crops came on the market. Since 1990 Roundup use has been on the rise, and roundup ready crops only came on stream in late 1990s, with corn not being used until 2,000. I have discussed the “non-link” between GMO and Roundup before in
Yes you are right about corn, however soybeans were the first round-up ready crops way before corn. Pay close attention to the graph in the link provided below. It does match your accounts of corn and mine for soybean. Very strong (facts) links between the introduction of GMO round-up ready crops and the use higher consumption of glyphosate…
https://uspirg.org/issues/usp/ban-roundup
Education is power…
It is not true for wheat either. Roundup was already in use in the 1970’s with increases each year. GMO wheat was invented in the early 2,000’s,k but Monsanto never went ahead with the product. From Wiki As of 2015, no GM wheat is grown commercially, although many field tests have been conducted”. https://en.wikipedia.org/wiki/Genetically_modified_wheat
How can you claim the increase in Roundup is due to GMO wheat, when we are not growing it?
I have heard that many farmers in the mid-west use Roundup on conventional wheat to help the fields ripen more evenly before combining begins. I cannot verify this. We don’t grow much wheat here in Maine, but to my knowledge, Roundup is not used on the grain crops that we are commonly grown here such as oats or winter rye.
A quick check on this shows that in most of the US, Roundup is not used to hasten wheat ripening. It is used in Canada due to a shorter growing season, and probably in some northern mid-west states.
This link gives some facts on the matter. https://www.huffingtonpost.com/jenny-dewey-rohrich/the-truth-about-toxic-wheat_b_6180498.html
Only about 5% of US wheat is sprayed at harvest time.
The amounts sprayed are extremely small. The link goes through a calculation similar to the one in my post to show that almost no Roundup ends up on the wheat. Clearly showing the importance of knowing the dose before reaching any conclusion.
The stories about “Poisoned Wheat” is just another example of fear-mongering by the anti Roundup crowd.
I’m sorry I missed the point, where did I mention anything about wheat.. but since you did bring wheat into the blog… the crop proved no commercial viability. The GMO wheat failed field tests year after year, and therefore, it has nothing to do with the rise of use of glyphosate…
Sorry – you didn’t – you said Soybean.
Thank you for your robust defence to the doubters in your comments column. I frequently write on my blog about the practical use of glyphosate in the garden and occasionally I get links sent to me by earnest readers who think I am misguided. Most of the links are gobbledegook and I cannot bring myself to defend myself – although I have done posts discussing issues. One of the links I was sent started with ” millions of US citizens use Roundup on their lawns”. Well really!
Congratulations on developing such an intelligent discussion with your readers.
Did you not know that US citizens now use Roundup Ready grass? 🙂
Come to think of it – I bet such a product would be very popular.
Absolutely! I’d be first in line!
I hope you continue with this series as many things need bunking/debunking. Does manure with residue kill plants? A common thing i read is “my soil is lifeless” or “my soil is sterile” because previous owner used x to kill weeds.
Please please continue.
Don’t worry – many more myths to come.
Herbicide residue in manure can harm plants. The big question – how big of a problem is this.
Re: “my soil is lifeless” – naturally, all soil is lifeless. But life forms live in soil. I talked a bit about this in https://www.gardenmyths.com/tag/fertilizer-salts/
Thank you Robert. Good work as usual. Two thoughts come to mind:
I wish the rather simple principle of cost/benefit analysis was taught to every high school student in America. Or junior high student. A twelve-year-old is quite capable of grasping the concept.
Second, it has been my decades-long experience that emotion-based thinkers can only rarely be persuaded, to any degree, by facts.
Agree on both points.
I have to write about this one day, but over the years I have found that almost all arguments with two sides have one side that is looking at facts, and the other, emotion. I think fact-thinkers can more easily see both sides of an argument.
I wish many things of value were taught in school, instead of what is currently being taught. As one example, why is studying literature so much more important than critical thinking?
Thank you for the succinct explanation
I agree that manual labour for weeding unwanted/invasive species is better…but find someone to do that backbreaking work? Riiight. Spraying it from airplanes in large quantities seems to be leading the same direction as DDT…the miracle chemical that was overused. The DDT controversy is interesting too, Robert, hope to see you write about that, as the complete ban resulted in a lot of human deaths, and it turns out that lesser quantities give good results and it is beginning to be used again. Wasn’t marijuana an evil chemical once too? I love the numbers work you have done here, and will share. It is a far less damaging impact on an ecology (is prohibited in wetland use) than the unmitigated spread of invasive species, since any local ecology rests squarely on the shoulders of its native plants.
A very common problem with most peoples opinions is that they don’t evaluate the alternatives and look at the harm or benefits of them. For example, lets say we ban glyphosate – what happens? Food production goes down. Food prices go up. There is less food to feed people and fewer people can buy it. What happens? How many people starve to death because of the ban?
Why don’t you do an article on people who seem to grow a lot of food without using roundup. Why don’t you try on the myth of how to grow good without roundup. I know several people who do this. It is possible. Open your mind.
I never said you need Roundup to grow food? Where did you get the impression that I believe such a thing? I don’t use Roundup in my vegetable garden.
The problem is that our whole agricultural system cannot stop using Roundup and keep producing the same level of food on the same current agricultural land.
“The problem is that our whole agricultural system cannot stop using Roundup and keep producing the same level of food on the same current agricultural land.”
This in and of itself is a myth.
Prove it.
One thing you fail to mention, since you just read the abstract, is that glyphosate is stable in water, meaning it doesn’t degrade, it actually accumulates. So yes, as you state, it does start with small numbers, but over time you neglect to state the consequences. Mercury is also safe in small numbers…
http://www.who.int/water_sanitation_health/dwq/chemicals/glyphosateampa290605.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756530/
Assuming glyphosate does accumulate in water, it would need to accumulate for hundreds if not thousands of years before it reaches a level that makes any difference to these numbers.
But, you statement “glyphosate is stable in water, meaning it doesn’t degrade” is not correct. From the reference below, which happens to be an acepted source of info on pesticides: “The median half-life of glyphosate in water varies from a few days to 91 days”, which is quite quick compared to many compounds.
http://npic.orst.edu/factsheets/archive/glyphotech.html
Thanks for doing this post. I agree with you that discussions of health effects of toxic chemicals in are often done without a good scientific context. Detecting the presence of a chemical is very different than documenting a concentration level that poses a health risk. All the studies I have seen show that when used properly especially for spot applications it should be quite safe to use.
What many people do not understand is that the dose – the amount – is critical when talking about the health effects of chemicals.
Thank you for this article/post. My concern is with “Round Up Ready” crops which can take up the glyphosate into the plant without dying so likely has residue within it. Even so, I have yet to see any firm evidence that this is dangerous. I have always heard that glyphosate is very water soluble, but once in the soil, it attaches well and does not leach out during the process of it breaking down. Thank you for getting breaking this down and squeezing the facts out of it!
Round Up Ready is a different potential problem. A couple of facts. Weeds formed a resistance to glyphosate before we started using Round Up Ready crops, so the crops did not cause the problem. Secondly, for most crops it is very unlikely the Ready gene will be transferred to weeds.
Glyphosate is absorbed by soil and held fairly tightly, but that does not mean it won’t move in soil. It also has a short half life so it degrades fairly quickly compared to other chemicals. This does not mean some of it does not make it to water ways.
Sorry, I guess I didn’t state that very clearly. I meant that RUR crops, such as sweet corn for instance, would take up the glyphosate without dying and then end up in the ear of corn which we eat. I have no idea what the concentration would be in a case like that. I wasn’t at all thinking about transference to weeds.
As we grow no GMO’s on our farm, we use Roundup almost exclusively in the fall for perennial weeds. We have lots of earthworms and bugs and our crop residues break down fairly quickly so I guess we have lots of microbes…….and we haven’t seen any 2 headed frogs yet either!
Please provide link for the resistance of weeds to round up. I have a different scenario supported by thousands of scientist that clearly state superweeds originated after the use of glyphosate.
Link to Union of Concerned Scientist, a group almost completely funded by its science community base members…
http://www.ucsusa.org/food_and_agriculture/our-failing-food-system/industrial-agriculture/the-rise-of-superweeds.html#.WhMn9tQrKf0
These superweeds now require 2-3 times the amount of glyphosate. Now as you state, weeds formed a resistance to glyphosate before the start of use of Round Up Ready crops, which defies all logic. If resistance was present in weeds defeatist to create a crop that resist glyphosate and just treat the weeds which already have resistance.
“Secondly, for most crops it is very unlikely the Ready gene will be transferred to weeds.” Transfer of DNA is only done at the ovary level of any seed producing plant and often only for plants in the same family but usually within the same genus. Thus GMO corn genes will not be found in any dicotyledon flora. However, GMO corn DNA has been found in native species of corn (huge problem there).
Finally, “It also has a short half life” does not mean it vanishes quickly. If you start with 100 and it has a half life of a month it means only half will degrade in a month so you end up with 50. Half of the next 50 will degrade in the next month and so on. Degradation not so quick now…
Not sure why you write all this? The post has nothing to do with weeds.
I agree Roundup has resulted in Roundup resistant weeds – nobody disputes that fact.
Since Roundup was used before GMO crops were introduced, it can certainly produce Roundup resistant weeds. None of this has anything to do with GMO crops.
Re:” “It also has a short half life” does not mean it vanishes quickly.” – actually it does mean this – A chemical with a short half life vanishes faster than one with a long half life.
The criticism by some concerning weeds developing resistance to Roundup is in itself a good example of how the public (not trained in chemical and biological sciences) fail to understand the broad context. That weeds developed a resistance to Roundup is not unique, nor is it alarming, disastrous, or even unexpected. Over time, organisms develop resistance to chemicals, both synthetic and organic, as well as resistance to naturally occurring pathogens and diseases. One of the main motivators of the synthetic chemical industry was the fact that by the 1950s, insects had developed resistance to the lead arsenate (organic) widely used to control the devastation of food crops, particularly the Florida citrus industry, by these insects. The human body is a prime example of organisms developing resistance to pathogens over thousands of years. In agriculture, scientists do not become alarmed when insects and fungal diseases adapt to their environment, they plan for it and work to stay several steps ahead.